SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b93ca62db783db8ea32139057680e270f75a89e4227eb92f7dab4f759bdc493' 
  AND token = 'qKR5RVmwSG1yXeXDC2SrnoqPULXzxcbScRmWg+uzsbg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}